Indeed, assuming the nonperturbative Regge bound (REF ), we can
consider the \((-2)\)  subtracted dispersion relations for \(f(s,u)\)  which
expresses \(- {8 \pi G /s}\)  in terms of the contribution of heavy
states, cf. equation (3.37) in
Ref. [1]}. Existence of such a dispersion
relation in the absence of supersymmetry is crucially due to the fact
that we consider gravitons as external states.
